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在OMF出现之前(9i R1),oracle db的文件，主要指dbf，redo，ctl是通过os管理的，为了简化对数据库文件的管理，oracle引入了OMF,通过omf创建的dbf和redo，其default的大小都是100m，autoextend umlimited。9i R1的dbf文件格式default：ora_%t_%u.dbf,redo格式：ora_%g_%u.log;9iR2的格式发生了一些变化，把ora变成了o1_mf_%t(%g)_%u.dbf(log),其中%t表示dbf所属的tbs，%g表示redo所属的group#,%u表示唯一。[@more@]1、仅设置参数db_create_file_dest创建redoSQL> show parameter db_createNAME TYPE VALUE------------------------------

没有role完全可以控制权限的使用，只是不够灵活和方便而已，那么角色的作用到底是什么呢？简单的归结为2条：1）实现批量授权2）动态控制权限[@more@]1、角色的作用a）实现批量授权b）动态控制权限2、使role生效或者失效SQL> create role rl1;角色已创建。--可以为role设置password，防止他人随意设置roleSQL> create role rl2 identified by rl2 ;角色已创建。SQL> select * from dba_role_privs where grantee='XYS';GRANTEE GRANTED_ROLE ADM DEF------------------------------ ------------------------------ --- ---XYS DB

1、系统权限UNLIMITED TABLESPACE 不能被授予role，可以被授予用户！2、UNLIMITED TABLESPACE 没有被包括在resource role中，但是UNLIMITED TABLESPACE 随着resource的授出而被授予用户的。3、UNLIMITED TABLESPACE 不能伴随着resource被授予role而授予用户。[@more@]1、测试1系统权限UNLIMITED TABLESPACE 不能被授予role，可以被授予用户！SQL> create role rl1 ;角色已创建。SQL> create user test identified by test;用户已创建。SQL> grant connect , create table , unlimited tablespace to rl1;grant connect , create

hostname方式是通过client端hostname连接数据库，无需配置tns！[@more@]1. HOSTNAME修改listener.ora中的如下信息(SID_DESC =(GLOBAL_DBNAME = your_hostname) --你的机器名(ORACLE_HOME = E:oracleora92) --oracle home(SID_NAME = orcl) --sid name)然后在客户端的sqlnet.ora中，确保有NAMES.DIRECTORY_PATH= (HOSTNAME)无需在client端配置tns测试一下：C:>sqlplus xys/manager@xysSQL*Plus: Release 10.2.0.1.0 - Production on 星期四 6月 26 09:56:03 2008Copyright (c) 1982, 2005, Oracle. All rights reserved.连接到:Oracle D

SYS_CONTEXT函数非常有用，和系统触发器结合起来可以很好的实现审计功能！[@more@]selectSYS_CONTEXT('USERENV','TERMINAL') terminal,SYS_CONTEXT('USERENV','LANGUAGE') language,SYS_CONTEXT('USERENV','SESSIONID') sessionid,SYS_CONTEXT('USERENV','INSTANCE') instance,SYS_CONTEXT('USERENV','ENTRYID') entryid,SYS_CONTEXT('USERENV','ISDBA') isdba,SYS_CONTEXT('USERENV','NLS_TERRITORY') nls_territory,SYS_CONTEXT('USERENV','NLS_CURRENCY') nls_currency,SYS_CONTEXT('USERENV','NLS_CALENDAR') nls_calendar,SYS_CONTEX

1. 对read only tbs进行热备份时不需要执行begin backup；2.从9i开始通过备份的controlfile对只读表空间进行恢复时不再需要把read only tbs对应的数据文件设置为offline[@more@]http://www.hackhome.com/InfoView/Article_164468.html也可以参考这个，写的更周全详细一些！1.SQL> alter tablespace users read only;表空间已更改。SQL> alter tablespace users begin backup;alter tablespace users begin backup*第 1 行出现错误:ORA-01642: 只读表空间 'USERS' 无需开始备份SQL> alter database backup controlfile to trace;数

Partial checkpoint– Dirty buffers belonging to the tablespace– ALTER TABLESPACE BEGIN BACKUP– ALTER TABLESPACE tablespace OFFLINE NORMAL上面2种操作会发生局部检查点！使相应的dirty buffer被写入和tablespace对应的datafile中[@more@]SQL> select name , checkpoint_change# from v$datafile;NAME CHECKPOINT_CHANGE#-------------------------------------------------- ------------------E:ORACLEPRODUCT10.2.0ORADATATESTSYSTEM01.DBF 806682E:ORACLEPRODUCT10.2.0ORADATATESTUNDOTBS01.DB 806682FE:ORACLEPRODUCT10.

http://yumianfeilong.com/2007/04/02/how-to-dump-redo-log-file-information/一篇不错的文章转[@more@]http://yumianfeilong.com/2007/04/02/how-to-dump-redo-log-file-information/

The objective of tuning a system is either to reduce the response time for end users of the system, or to reduce the resources used to process the same work.[@more@]The objective of tuning a system is either to reduce the response time for end users of the system, or to reduce the resources used to process the same work. You can accomplish both of these objectives in several ways:Reduce the Workload Balance the Workload Parallelize the Workload Reduce the WorkloadThis is what commonly constitute

The NOREWRITE hint disables the use of function-based indexes.看到这句话之后不太理解为什么提示NOREWRITE 的使用会丧失基于函数index的使用能力！[@more@]出处：http://download.oracle.com/docs/cd/B10501_01/server.920/a96533/hintsref.htmThe NOREWRITE hint disables the use of function-based indexes.看到这句话之后不太理解为什么提示NOREWRITE 的使用会丧失基于函数index的使用能力！

本人在大连，面向全国各地长期提供专业的oracle培训！有oracle培训需求的客户可以联系我！培训的形式大致分两种：1、类似官方培训，以官方的培训讲义为基础结合讲师多年来的实践经验和培训经验为有oracle培训需求的企业或者个人提供最优质的服务；2、企业定制培训，完全根据客户自身的需求为企业或者个人量身定制培训。培训的内容：1、和开发相关的内容，主要介绍sql、plsql的使用；2、oracle数据库的基本概念，基本管理，体系架构；3、详细介绍oracle数据库的备份恢复原理、手段以及备份恢复策略的制定等；4、详细介绍数据库的性能优化，

doc上的原话，记录一下，感觉写的很精彩！[@more@]Steps in The Oracle Performance Improvement MethodGet candid feedback from users. Determine the performance project's scope and subsequent performance goals, as well as performance goals for the future. This process is key in future capacity planning. Get a full set of operating system, database, and application statistics from the system when the performance is both good and bad. If these are not available, then get whatever is available. Missing s

定位系统性能瓶颈的时候要多利用数据以及统计信息等资源而不要过多的依赖自己以前积累的经验想当然。因为今天的系统已经变的非常复杂，性能分析的一些浮浅的规则不容易产生。oracle性能改进方法论定义的是一种工作的方法而不是一组权威性的规则。在定位性能瓶颈的时候，最好的规则就是没有规则（With bottleneck detection, the only rule is that there are no rules!The best performance engineers use the data provided and think laterally to determine performance problems.）[@more@]The Oracle performance improvement method

从下面的doc理解，如果单一的应用程序跑在oracle数据库服务器上，那么（On an Oracle data server system, where there is generally only one application running, the server runs database activity in user space. Activities required to service database requests (such as scheduling, synchronization, I/O, memory management, and process/thread creation and tear down) run in kernel mode. In a system where all CPU is fully utilized, a healthy Oracle system runs between 65% and 95% in user space.）oracle对系统

http://space.itpub.net/756652/viewspace-244138转，不错的文章！[@more@]http://space.itpub.net/756652/viewspace-244138

http://www.itpub.net/thread-148366-1-2.html记录一下![@more@]http://www.itpub.net/thread-148366-1-2.html

什么是Scalability，看看他的形容词的意思：scalable adj.可攀登的可升级的，这里Scalability我通常理解为系统的可攀升能力。doc的原意是：Scalability is a system's ability to process more workload, with a proportional increase in system resource usage. In other words, in a scalable system, if you double the workload, then the system would use twice as many system resources. This sounds obvious, but due to conflicts within the system, the resource usage might exceed twice the original workload.[@more@]Un

不知道该起个什么样的标题来记录这句话，看到这句话时感觉写的非常好，想记录一下：Performance problems are usually the result of contention for, or exhaustion of, some system resource性能问题通常是一些系统资源被争夺或者是被耗尽的结果！[@more@]Performance problems are usually the result of contention for, or exhaustion of, some system resource --===========================================从另外的角度来讲：性能问题来至于：Performance problems generally result from either a lack of throughput, unaccept

What Is Disk Contention?Disk contention occurs when multiple processes try to access the same disk simultaneously. Most disks have limits on both the number of accesses (I/O operations each second) and the amount of data they can transfer each second (I/O data rate, or throughput). When these limits are reached, processes must wait to access the disk.[@more@]What Is Disk Contention?Disk contention occurs when multiple processes try to access the same disk simultaneously. Most disks have limits o

http://www.itpub.net/thread-877110-1-5.html收藏记录一下！[@more@]http://www.itpub.net/thread-877110-1-5.html